MIMO (Multiple Input Multiple Output) is a range of technologies used to multiply the capacity of a wireless connection without requiring additional spectrum. At their most basic level, wireless communication systems can use a single antenna element to communicate with each other. This is known as a single polarization system.
By becoming a dual polarization system - adding another antenna element to each wireless node the network capacity can be doubled without requiring more spectrum by using the horizontal and vertical polarity of the radio wave, each carrying a separate data stream to transmit and receive data.
This is also referred to as a 2x2 MIMO system, as both wireless nodes which are communicating with each other have two antenna elements. The first number refers to the number of transmit antennas, the second to the number of receive antennas used to communicate over the radio channel at any moment. Through the use of dual polarization antennas at each end of the link, a 2x2 MIMO system can typically support two streams in the same radio spectrum.
ePMP 1000/2000 are 2x2 MIMO systems.
Historically, MIMO technologies have been used to increase capacity between two wireless nodes. This benefits one subscriber at a time. As network operators aim for the highest utilization of their network possible, this is not ideal.
A recent development is to use these technologies to allow an access point (AP) to communicate to several subscriber modules (SMs) at once. The ePMP 3000 system, when operating in MU (Multi User) MIMO mode, is capable of communicating with two SMs at once. This allows the network operator to both increase network capacity and better utilize the spectrum.
To benefit from MU-MIMO, the AP antenna must be capable of beamforming. For ePMP 3000 that is achieved by usage of 4x4 antenna array with dual polarized radiating elements spaced horizontally.
Beamforming is based on channel measurement mechanism implemented via sounding procedure. Only new SMs of F300 series are capable of beamforming sounding. Accordingly, legacy SMs are not supported for downlink transmission modes based on beamforming.
When ePMP 3000 transmits downlink data to a single (beamforming capable) SM a 4x2 Single User (SU) MIMO mode is used. Beamforming allows to radiate energy directionally towards SM.
When ePMP 3000 transmits downlink data to two (beamforming capable) SMs in 4x4 MU-MIMO mode it radiates two directional beams. Beam for each SM is formed in a way that null of the synthesized antenna pattern is directed towards paired SM in order to suppress inter-interference. Accordingly, SMs must be separated by some angle to allow MU-MIMO.
Through the combination of MIMO (H+V polarization), beamforming and highly efficient channel sounding, a MU-MIMO system can be created. ePMP 3000 the industry’s first commercially deployed affordable multi-user multiple-input multiple-output (MU-MIMO) platform.
ePMP 3000 4x4 Sector Antenna